Telephone-exchange system



F. A. STEARN AND F. J. SCUDDER.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED AUGJ, 1920.

Patented NOV. 1, 1921..

H SHEETS-SHEET I.

Frank/in A. jfearn. Frederick J Scam afar F. A. STEARN AND F. I. SCU'DDER.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED AUG.7,1920.

Patented Nov. 1, 1921.. j

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Freda/"k J Scuade/r F. A. STEARN AND F. J. SCUDDER.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION F[LED AUG.7, 1920. 1,395,??? Patented Nov. 1, 1921.

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. APPLICATION FILED AUGJ, I920- I I 1,395,977,, Patented Nov. 1, 1921 H $HEETS-SHEET 4.

F. A. STEARN AND F. J. SCUDDER. TELEPHONE EXCHANGE SYSTEM.

Y I APPLICATION FILED AUG.7, 1920. 1,395,977, I' Patented Nov. 1, 1921.

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CDE-) F. A. STEARN AND F. J. SCUDDER. TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED AUGJ, I920. 1,395,977., Patented Nov. 1, 1921.

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APPLICATION FILED AUG.7,1920.

Patented Nov, 1, 1921 19395997??? 1 SHEETSSHEET7 Ir) ver; fora Frank/l A. Jfearn.

F. A. STEARN AND F. 1. scunnm.

TELEPHONE EXCHANGE SYSTEM.

' v APPLICATION FILED AUGJ, 1920- v I 1 35 971, Patented Nov. 1, 1921c. I H SHEETS-SHEET 8.

fieder/b r J Scudden F. A. STEARN AND F. 1. scunnta.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED AUGJ, 1920.

Patented NOV-1, 1921;

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Frederick J ficudder."

,F. A. STEARN AND F. J. SCUDDER. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED AUG.7, 1920- 1,395,977, 'Patentefi Nomi, 1921.

H SWEEYS-SHEET l9.

. brushes of the switches are provided with a surge PATT crews.

FRANKLIN A. STEARN, or PATERSON, NEW JERSEY, AND FREDERICK .1, scUDDEB, or

LONG ISLAND, NEW YoaK, ASSIGNORS T0 WESTERN ELECTRIC COMPANY, m roaa'rnn, or Nnw' oax, N. Y., A CORPORATION on NEW roan.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent. Pat t d N 1 192 Application filed August 7, 1920. Serial No. 402,041.

To all whom it may concern i Be it known that we, FRANKLIN A. STEARN and FREDERIC J. SCUDDER, citizens of the United States, residing at Paterson, county of Paterson, State of New Jersey, and at Long Island,'in the county of Queens, State of New York, respectively,'have mvented certain new and useful Improvements 1n Telephone-Exchange Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to a telephone system and more particularly to a system in which connections are established between subscribers lines by means of mechanical switching devices.

In large telephone exchanges comprislng several ofiices, some of which may be closely associated and others of which may be quite widely separated, it is desirable to employ inter-office trunk lines for connecting the different offices of the exchange and for extending connections to toll trunks leading to exchanges in distant communities, that are designed to provide the most efficient talking conditions. This result is attained by providing the trunk lines which extend to distant offices or to distant exchanges with loading coils and by omitting such loading coils from inter-office trunks which connect adjacent offices.

Heretofore it has been the practice in large exchanges in which connections are extended by mechanical switching dev ces, to provide select r switches in the originating ofiices which are under the control of a common oiiice sending mechanism for extending connections to trunks leading to other offices, or to other switche local to the originating office. These switchesare positioned in accordance with the office designations of the lines with which the connections are de sired. The talking circuits extending to the repeating coils for increasing the efficiency of speech transmission, talking current be-.

ing supplied to the line of thejcalling subscribers through the primary windings of' these coils.

To attain the most efficient transmissionof speech through the windings of the repeating coils and over the difierentclasses of inter-office trunks with which connection may be established, it is desirable to provide for different ratios of transformation through the windings of the repeating coils, that is, a greater ratio of transformation if the outgoing oflice trunk is of considerable length and loaded, than if the trunk is of short length and without loading. It is also desirable to completely by-pass the repeating coils by direct metalliclconnections when connection are extended to an operators po sition. It is therefore the objectof this invention to provide means under the control of the office sender for altering the connections of the repeating coil in the talking circult extending between a calling subscribers' line and a desired trunk circuit in accord-; ance with the character of the trunk circuit to which the connection is extended.

This object is attained by selectively con- I trolling the movements of the sequence switch associated with the district selector to increase or decrease the number of effective turns in the secondary winding of the repeating coil associated with the district selector or to establish a metallic by-pass around the repeating coil.

In connection with this invention the office sender is provided with a plurality. of

district and oflice selector switches to extend the call to the office in which the desired line terminates, and other of the relays through cooperation of. the counting relays control the selective movements of the district sequence switch for thepurpose of alt 1ering the connections of the repeating coi v The invention may be more readily understood by reference to the following description considered in connection with the accompanying drawings in which Figure 1 shows oneof a group of lines terminating in a full mechanical oflice of the exchange and a rotary line switch individual to such line by means of which the subscribers line may be connected to an idle district selector a sender finder switch, together withthe I circuits and controlling mechanism associated therewith; Fig. 3 shows an oflic e selector switch together with the clrcults and controlling mechanism associated therewith;

Fig. 4 shows an incoming selector switch provided with mechanism for applying ringlng current to the terminals of a called 11116, together with the circuits and mechanism for controlling such switch; Fig. 5 shows the mechanism and circuits of a final selector switch and the line of a subscriber to which the selector switch has access; Fig. 6 shows a time measure switch and translator control sequence switch associated with the central oflice sending mechanism; Fig. 7- shows a portion of the circuit of a sending mechanism comprising a stepping relay, a group of counting relays, a sequence switch for controlling the circuits of the sender,

and aclass sequence switch for altering the circuits of the sender in accordance with the class of the call which is to be extended; Fig.8 shows the code registers which are set in accordance with the first three code or office designation digits dialed by the calling subscriber, and the steering switch which successively associates the code registers and the number registers shown m Fig. 9 with the. impulse circuit extendlng to the calling subscribers line; Fig. 9 showsnumberregisters which are set by the calling subscriber in accordance with the numerical designation of the desired line; Fig. 10 shows groups of translator register reflays which areselectively operated by the translator switch and pulse machine shownin Fig. 11 in accordance with the setting of the code registers for determining the setting of the class switch shown-in Fig. 7, the setting of the district selector shown in Fig-3 and for setting the sequence switch of the district selector to determine the connection of the repeating coil into the talking circuit. Fig. 11 shows a translator switch and a development of the pulse machine drum for setting the register relays; and- Fig. 12 is a diagram showing the manner in which the several sheets of the drawing should be arranged to-show as much of a complete organization of circuits as is necessary to illustrate the manner in which the connections maybe established between subscribers lines.

'The calling subscribers line K is of the usual type provided with a transmitter, re- .ceiver and a call bell and since it terminates in a full mechanical exchange is also equipped with an impulse sending dial S of the usual type.

The subscribers line terminates in an individual trunk finding switch of the well known rotary step by step type which, through a plurality of wipers, has access .coming selector-and final selector diagrammatically disclosed in Figs. 2 to 5 inclusive are of the type shown and described in the patent to E. B. Craft and J. N. Reynolds No. 1,123, 696 issuel January 5, 1915. Each of the switches has a vertically disposed switch shaft provided with five sets of brushes, each brush 'set having access to a bank of 100 terminals. For driving the switch shaft upwardly an up-drive magnet is provided which when energized presses the switch shaft against a constantly driven power drum, and for restoring the switch shaft to normal position a second downdrive magnet ,is provided which when energized presses the switch shaft against a second constantly driven power drum. For determining the particular set of brushes on the switch shaft to be employed a tripping spindle is provided as described in the patent 'hereinbefore referred to. The final selector switch differs from the other selector switches in being provided with additionalmeans comprising a second up-drive magnet and driving drum for driving the switch shaft upwardly at two different speeds,

rapidly during brush selection and group selection, and more slowly during the terminal selection-movement of the switch shaft.

The translator switch TS shown in Fig. 11 is of the same type as the switch shown in the aforesaid patent, but is equipped with 10 sets of brushes arranged in five pairs, the

brush sets comprising each pair being ar-' ranged to be tripped together.

The sender finder switch SF shown in Fig. 2, the time measure switch TM shown. in F i 6, the register steering switch RS shown in Tig. 8 and the registers A, B, C, TH, H, T and U shown in Figs. 8 and 9 are of the well-known step by .step type, the wipers of which are advanced by stepping magnets. With the exception of sender finder switch SF, the wipers of these switches are restored to normal positionby, being advanced by their respective stepping magnets around to normal. Finder switch SF has no normal position, the wipers thereof resting in contact with the bank terminals last employed and are arranged to be variously connected to the contacts in the 10 banks of translator switch TS through suitable distributing blocks (not shown) for conducting impulses of current from the several segments to the bank terminals of the translator switch.

For controlling the circuits associated with the several selector switches and the circuits of the office sender, auxiliary switches are provided. These switches may be of the type described in the patent to Reynolds et al, No. 1,127,808, issued February 9, 1915 and known in the art as sequence switches. Each sequence switch comprises a rotatable shaft driven from a constantly operated source of power through a magnetic clutch member and carries a plur rality of circuit closing cams which at different radial positions of the shaft cause the closure of a plurality of contacts; The cam contacts associated with each sequence switch are closed only in the positions indicated by the numerals associated with each contact with the exception of the master contacts 201, 301, 401, 501, 601, 701 and 751 associated respectively with sequence switches 200, 300, 400, 500, 600, 700 and 750, these latter contacts being open in the positions indicated by the numerals appearing adjacent such contacts and closed in all other positions.

The different pieces of apparatus employed in the system having now been briefly described it is thought that a clearer understanding .of the invention may be had from a description of the method of establishing a' call from the station of the calling subscriber K in an originating office X to the station of a called. subscriber L'whose line terminates ina terminating office '-Y. The apparatus'shownin Figs. 4 and 5 is located in office Y, whereas the remaining apparatus is located in the originating office X. It .will first be assumed that the oflices X and Y are situated adjacent to each other and.

that therefore the interofiice trunk is short and without loading and that the designa tion of the desired line is LISpenard 9532.

Initiation of full mechanical call.

101, the innermost lower armature and back contact offcutoff relay-102, over line conductor 103, through the substation of subscribers line K, and thence back over line conductor 104 to ground at the upper armature and back contact of. cutoff relay 102.

.The line relay energizes in this circuit and closes a circuit for the stepping magnet 105 of the switch 100, which circuit may be traced from grounded battery through the winding and armature contacts of magnet 105, conductor 106, the lowermost armature and back contact of relay 102, the right hand armature and front contact of relay 101, conductor 107 and thence to ground through the wiper 108 and the normal contact of the bankto which this wiper has access. -The magnet 105 upon energizing .in'this circuit advances the wipers 108, 109, 110, 111, 112 and 113 of switch 100 to the second contacts of the respective banks to which they have access. As the second contact which wiper 108 engages is permanently connected to ground, the magnet 105 continues to step the wipers to the third set of contacts leading to the first of the group of trunks to which the switch 100 has access.

If the first trunk of the group is busy, there will be aground potential on the test terminal thereof appearing in the lowermost bank of the switch and the switch will therefore continue stepping until an idle trunk is found, upon the test terminal of which battery potential appears. When this battery potential is encountered a circuit is conductor 115 and thence to ground through both windings of cutofi' relay 102. The en- .ergization of the cutoff relay 102 opens the circuit of the stepping magnet 105 at its lowermost armature and back contact and at its upper armature and back contact, and at its upper armature and front contact and uppermost lower armature and front contact, this relay extends the conductors 103 and 104: of the subscribers line to the wipers 111 and 113 of the switch 100 and thence to the trunk conductors 116 and 117 leading to the selected district selector. Relay 102 also at its intermediate lower armature and front contact closes a circuit extending through the right hand winding of sleeve relay 226 ofthe district selector switch, through the break contacts of the left hand armature of slow releasing relay 227, the lower right hand contact of sequence switch cam 203 (1 to 2}) sleeve conductor 118, wiper 109, winding of the marginal'message register magnet 119, conductor 120, the intermediate lower armature and front contact of cutofirelay 102 and thence to ground through the upper winding of the cutoff relay. The sleeve relay 226 of the district selector switch energizes in this circuit, but owing to its marginal na-. ture the message-register magnet 119 does not energize at this time.

For making the calling subscribers line "conductor 125 to the .back contact of the right hand armature of line relay 101 preparatory to restoring the finder switch to normal when the cut-off relay 102 becomes dei nergized upon the termination of the connection.

Upon the energization of sleeve relay 226 a circuit is established for the line relay 228 of the district selector switch 250 which circuit extends from grounded battery through the right .hand winding of this relay, the

lower right hand contact of sequence switch cam 204, conductor 229, the lower contacts of sequence switch cam -205, conductor. 230 and thence to ground through the front contact and right hand armature of sleeve relay 226. At its inner left hand armature and front contact relay 226 connects ground potential to I the testconductor 114 of the selected trunk to mark the trunk busy to other line switches, and at the back contact of this armature disconnects the source of battery potential which up to the time the selector switch was seized marked the selector switch as idle. Line relay 101 now denergizes.

Relay 228 upon energizing, closes a circuit for driving the sequence switch 200 of the district selector switch out of it normal position 1 and into position 2, this circuit extending from grounded battery through the magnet winding 200, conductor 231, the upper left hand contact of sequence switch cam 206, the inner right hand armature and front contact of relay 228 and thence to ground at the lower right hand contact of sequence switch earn 207 The sequence switch magnet energizes inthis circuit and under the control of the master cam 201 drives the se quence switch into position 2 in which position a circuit is closed from grounded battery through the winding of relay 227, the upper left hand contactof sequence switch cam 208 and thence to ground. Relay 227 upon energizing .closes a locking circuit for the sleeve relay 226 extending through the right hand winding of relay 226, the make con tacts of'the left-hand armature of relay 227 and thence to the. sleeve conductor 118 over the upper right hand contact of sequence switch cam 203 (1% to 16) this circuit being maintained through position 16 of the sequenc e switch or until relay 227 becomes deenergized. Upon reaching position 2 the sequence switch connects a new holding ground to the test conductor 114 extending over conductor 232 and through the upper right hand contact of sequence switch cam 208, whichholding ground is maintained through position 18;, of the sequenceswitch.

As soon as the sequence switch reaches position If} a circuit is closed for the\s te ping magnet 233 of the sender finder F extending from grounded battery through the interrupter contacts and winding of magnet 233, the upper left hand contact of sequence switch cam 209 (1% to 2) conductor 234 ahd thence to ground through the inner right hand armature and front contact of relay 228 and the lower right hand contact ofsequence switch cam 207. A circuit is also closed at this time through the winding of stepping magnet 233, the winding of cut in relay 235 and thence to ground at the lower left hand contact of sequence switch cam 208. Relay 235 does not energize at this time, however, since its winding is shunted by ground connected to the armature'of line relay. 228.

' As soon as sequence switch 200 leaves posi-.

tion 1 the initial energizing circuit of line relay 228 is opened at the lower right hand contact of sequence switch cam 204, but this relay remains looked over a circuit extending from grounded battery through its left hand winding, its left hand armature and front contact, the upper left hand contact of sequence switch cam 210, conductor 236, the

lower right hand contact of sequence switch cam 211, conductor 237, test wiper 238 of the sender finder switch SF and to ground at busy contacts of the bank over which this wiper moves. As soon, however, as an idle sender is found, the wiper 238 will find no ground on the terminal corresponding to such idle sender and the line relay 228 will thereupon denergize, opening at its inner right hand armature and front contact, the

circuit extending through the stepping magnet 233, and closing at its inner right hand armature and back contact a circuit for driving sequence switch 200 out of position 2 and into position 3. This circuit may be traced from grounded battery through the sequence switch magnet 200, conductor 231,

the upper right hand contact of sequence switch cam 206, the inner right hand armature and backcontact of relay 228 and thence to ground at the lower right hand contact of sequence switch cam 207.

As soon as line relay 228 deenergizes the shunt around the winding of relay 235 is removed at the inner right hand armature and front contact of relay -228,and relay 235 thereupon energizes in series with stepping magnet 233, the current flowing through this circuit, however, not being sufficient to cause the energization of the stepping magnet. circuit extending from ground through the inner left hand armature and front contacts of this relay ov'er wiper 23.8 and the terminal upon which it is resting, conductor 624 and Relay 235, upon energizing, closes a switch TM, extending'from grounded battery through the winding of stepping magnet 626. over wiper 627 and the normal contact of the bank with which it is associated,

through the interrupter 628, the outermost left hand armature and back contact of relay 629 and thence to ground at the armature and front contact of relay 625. Under the influence of the interrupter 628, the stepping magnet 626 advances the wipers of the time measure switch TM from their normal resting positions to the second position contacts in c the several banks of contacts to which'they have access respectively. With the wiper 630 in engagement with the second contact 631 of the bank with which it is associated, a circuit is closed for relay 629 which may be traced from grounded battery through the winding of this relay, over conductor 632, contact 631 and thence to ground through wiper 630.

Relay 629, upon energizing in this circuit, opens at its outer left hand armature and back contact the initial ste ping circuit of the time measure switch T and closes a new stepping circuit for advancing the time measure switch from position 2 into position 6, this circuit extending from grounded battery through the winding of stepping magnet 626. the armature contacts of stepping magnet 626, wiper 633, the Nos. 2 to .5 contacts of the bank with which this wiper is associated, which contacts are tied together, conductor 634, the outer left hand armature and front contact of relay 629 and thence to ground at the armature and front contact of relay 625. Relay 629 also closes a circuit extending from grounded battery through the winding ofstepping relay 800, conductor 801, the innermost left hand armature and front contact of relay 629, conductor 635, wiper 239 of the sender finder SF, conductor 240, the upper left hand contactof sequence switch cam 212 (2 to 109;) trunk conductor 117, wiper 113 of the trunk finding switch 100, upper armature and front contact of relay 102, line conductor- 104 through the calling subscribers sending dial S, line conductor 103, the innermost lower armature and front contact of relay 102, wiper 111, conductor 116, the lower left hand contact of sequence switch cam 213, (2 to 10%;) conductor 241, the outer left hand armature and front contact of relay 235, wiper 242 of the sender finder SF, conductor 636, the right hand'armature and front contact of relay 629 and thence to ground through the right hand winding of balancing resistancecoil 637. The stepping relay 800 energizes in this circuit and at its left hand armature and front contact closes a circuit for the slow releasing relay 802, this circuit extending from grounded battery through the winding of relay 802 and thence to ground through the left hand armature and front contact of relay 800. A circuit is now closed for sending a dialing tone to the calling subscriber which circuit may be traced from ground through the right hand make contacts of slow releasing relay 802, conductor 803, wiper 804 -of the steering switch RS, the normal contact 805 of the bank with which this wiper :is associated,

conductor 806, through the left hand winding of balancing coil 637 and thence to ground through the secondary winding of the tone coil 638. The tone current flowing in this circuit is inductively transmitted to the substation of the calling subscriber through the right hand winding of balancing coil 637, over the circuit previously traced. i

At the time the sender finder SF "seized the idle oflice sender and the time measure switch TM advanced out of its normal position, busy potential was connected to test conductor 624 to mark the office sender busy to all othensender finders to prevent the' sender from being taken for use after being released from a district selector until after it has been restored to normal condition over a circuit extending from ground through the wiper 639 of the time measure switch, the contacts of the bank with which this wiper is associated, conductor 640, conductor 641, the right hand winding of differential'relay 625 and thence to the test conductor 624. Relay 625, being differentially wound, is not affected by the current flowing over this path and through its left hand winding.

The calling subscriber receiving the dialing tone over the circuit preyiously traced, proceeds to dial the number of the desired line. Under the assumption that the subscriber desires a connection with a subscribers line L in an adjacent office, which subscribers line is listed in the directory as LISpenard 9532 and that this office is reached through a district selector switch 250 and office selector switch 350 local to the calling subscribers ofiice, and through an incoming selector 450 and a final selector 550 at the office in which the desired line terminates, the subscriber proceeds to dial three letters corresponding tothe oflice designation ofthe office in which the desired line is located and then dials four digits representing the number of the line in such office. In the case assumed, the calling subscriber will dial the letters L I S appearing through holes 5, 4 and 7 of the dial and will then dial the numerals 9 5 3 2. The three letters, which represent the office code, will not only cause the setting of the district selector and office selector switches to choose the desired office, but will also cause the selection of a proper talking path for eificient speech transmission bet-ween the offices and the setting of the class sequence switch 750 for determining the adjustment of the circuits of the oiiice sender in accordance with the class of the call which is being extended.

Setting the code and numerical registers.

In response to the first interruption of current in accordance with the first letter of the oifice designation dialed by the calling subscriber the stepping relay 800 deenergizes and closes a circuit for the stepping magnet 807 of the first code register A, which stepping circuit may'be traced from grounded battery through the lefthand armature and back contact of preliminary pulse relay 808, conductor 809, the winding of slow release relay 810, conductor 811, the winding of stepping magnet 807, the back contact and outer right hand armature of relay 808, the normal bank contact 812 of the register steering switch R s, wiper 813 normally in engagement therewith, conductor 814, the left hand armature and front contact of slow releasing relay 802 and thence to ground through the armature and back contact of stepping relay 800. In response to this impulse the stepping magnet 807 advances the wipers of the register A one step as soon asthe circuit of the stepping magnet 807 is again opened. Upon'the reenergization of stepping relay 800 and in response to successive impulses of the first code letter L having a numerical equivalent of digit 5, the register A advances its wipers 1 into contact with the fifth set of contacts .of

its banks. To insure that the stepping magnet 807 shall-remain energized long enough in this circuit and closes a locking circuit for itself independent of the armature contacts of relay 800, which locking circuit extends over the circuit previously traced through the winding of relay 841, through the armature and back contact of magnet 807, the.

outer right hand armature and back contact of relay 808, contact 812, wiper 813, thence to ground through'the left hand armature and frontcontact of relay 841. Relay 841 is thus maintained energized until stepping magnet 807 has moved its armature to the full extent of its movement, when the circuit through relay 841 is opened at the with the first contacts of the banks.

pendent of the energiza'tion of relay 800.

The slow releasing relay 810 which was also energlzed in the circuit of stepping magnet 807 of the register A, maintains its energization because of its slow releasing characteristic until the series of impulses transmitted through the magnet 807 ceases, when'this relay deenergizes. Up0n its initial energization, this relay closes a circuit extending from grounded battery through the make contacts of its left hand armature and the winding of slow releasing relay 815, and this latter relay through its armature and front contact connects ground potential to the conductor 640 for insuring that the ofiice sender be maintained busy to all sender finders during the setting of the register A. At its right hand armature and front con-- tact, relay 810 also closes a circuit extending from grounded battery through the winding of slow releasing relay 816, through the wlnding of stepping magnet 817 of the register steering switch RS, over conductor 818 through the right hand armature and front contact of relay810 and thence to ground over conductor 803, and the make contacts of the right hand armature of slow releasing relay 802. AS soon as relay 810 deenergizes, upon the cessation of impulses flowing through the circuit of stepping magnet 807, the circuit previously traced through relay 816 and stepping magnet 817 is opened, causing the deenergization of stepping magnet 817 which thereupon advances the Wipers of the register steering switch RS from engagement with the normal contacts of the respective banks to which they have access into engagement The movement of wiper 813 now transfers the control circuit extending from the armature of stepping relay 800 over conductor 814, from the winding of stepping magnet 807 of register A, to the winding of stepping magnet 819 of the register B. Slow releasing relay 816 which was energized in series with the stepping magnet 817 during its ene'rgizat-ion maintains a ground potential connected to the conductor 640 for holding the sender busy to all sender finders SF over a circuit extending from its armature and front contact to conductor 640.

With the register steering switch RS in position 1 the second'series of impulses corresponding to the second code letter of the oflice designation causes the setting of the code register B in a manner similar to the setting-of register A,the stepping circuit of the stepping magnet 819 of register B extending from grounded battery through the left hand armature and back contact of reits armature and front contact? closes a cirlay 808, conductor 809, the winding of slow releasing relay 810, conductor 811, the winding of stepping magnet 819, conductor 820, bank contact 821, Wiper 813 in engagement therewith, the left hand armature and front contact of relay 802 and thence to. ground at the armature and back contaet'of relay 800. Under the assumption that the second code letter is Ihaving a numeral equivalent of digit 4, the wipers of the code register B take a setting on the No. 4 contacts of the banks with which the respective wipers make contact. Upon the termination of the impulses of the'second code letter, the slow releasing relay 810 deenergizes in the manner previouslyv described; causing the movement of the register steering switch RS from position 1 into position 2, in which position the control circuit previously traced through the stepping magnet 810 of the code register B is opened and the control circuit extended through the stepping magnet 822 of the code register C. With the wipers of the register steering switch RS in engagement with the second position contacts of the respective banks with which they are associated, a circuit is established for the relay 642 which may be traced from grounded battery through the right hand winding of this relay, conductor 643, contact 823, wiper 804 in engagement therewith, conductor 803 and thence to ground at the make contacts of the right hand armature of relay 802. Relay 642 upon energizing, closes a-locking circuit for itself extending from grounded battery through its left hand winding and left hand armature and front contact to ground on conductor 640, and at its left hand armature and front contact closes a circuit for the control relay 644 of the translator control sequence switch 600. This circuit extends from grounded battery through the left hand winding of relay 644, the contact of sequence switch cam 602, (1 and 2.), the armature and front contact of relay 642 and thence to ground on conductor 640. v

Setting the translator Switch. Relay 644 energizes in this circuit/and at cuit' for driving the translator control sequence switch 600 out'of position 1- and into position 2, this circuit extending from grounded battery through the magnet winding of sequence switch 600, the left hand contact of sequence switch cam 603, (1) and thence to ground through the armature and front contact of relay 644. In its movement from position 1 to position 2the sequence switch is under the control of master contact 601 which insures that the sequence switch will move completely into position 2.-

Upon reaching position 2 sequence switch 600 closes a circuit for the up drive magnet 1100 of the translator switch TS, which cir- V cuit extends from grounded battery through the winding of magnet 1100, conductor 1101', the contact of sequence switch cam 604 (2) andthence to ground at the armature and front contact of relay 644. In response to its energization magnet 1100 presses the depending portion of the switch shaft 1102 of the translator switch TS against the constantly rotating up driveroller 1103 thereby causing'the switch shaft 1102 and the brush sets carried thereby to-be moved upwardly. This upward movement continues until the test brush 1104 encounters a terminal inthe test bank 1105 which has been grounded through the bank contacts of code registers A and B. As soon as brush 1104 engages such a terminal a secondary circuit is closed through the right hand winding of the differentially wound control relay 644 which may be traced from grounded battery lay, the left hand contacts of sequence switch cam 605, conductor 1106, testing brush 1104, terminal1107, conductor 1108, contact 824 and wiper 825 ofthe register A, conductor 826, contact 827 and wiper 828 of the code register B, conductor 829 and thence to ground at the lower left hand contact ofsequence switch cam 606 (1 to 3). Current flowing through the right hand winding of relay 644 differentially balances the relay which thereupon denergizes, opening at its armature and front contact the circuit previously traced through the up drive magnet 1100 of the translator switch thereby arresting the upward movement of the switch. The brush shaft of this switch is now positioned with a certain pair of the brush sets carried thereby in cotiperative relation with a tripping finger on the tripping spindl 1109. Relay 644, upon deenergizing, also closes a circuit for driving the translator control sequence switch 600 out of position 2 and into position 3, this circuit extending from grounded battery through the magnet winding 600, the upper left hand contact of sequence switch cam 607 (2) and thence to ground at the armature and back contact of relay 644.

Upon leaving position 2, the initial energizing circuit extending through the left hand winding of relay 644 was opened at the contact of sequence switch cam .602, and the secondary energizing circuit is opened at the upper left-hand contact of cam 605 as soon as switch600 leaves position 2%, but this circuit is again established as soon as the sequence switch reaches position 3 and the relay 644 therefore again energizes. Upon reaching position 3 a circuit is established for the tripping magnet 1110 of the translator switch TS,- extending from. grounded battery through the winding of the tripping magnet, conductor 1111 and thence to ground'through the upper right hand contact of sequence switch cam 608' (3 to 5). The tripping magnet upon energizing in this circuit, rotates the tripping spindle 1109 to position tripping fingers to trip the pair ofbrush sets of the switch TS which have been positioned in operative relation to a pair of tripping fingers on the tripping spindle upon a subsequent movement of the switch shaft. It will be assumed that brush sets 1112 and 1113 shown in Fig. 11 of the drawing are the brush sets which are to be tripped at this time.

Control relay 644, upon reenergi'zing in position 3 of sequence switch 600, again closes a-circuit for driving sequenceswitch 600 out of position 3 and into position 4, this circuit extending from grounded battery, through the winding of magnet 600,

the left hand contact of sequence switch cam 603 (3) and thence to ground through the armature and front contact of relay 644. 'hen sequence switch '600 reaches position 4 a circuit is again closed for the up drive magnet 1100 of the translator switch TS as previously traced, through the armature and front contact of relay 644. \Vhen the up drive magnet is thus energized, the switch shaft 1102 is driven upwardly and during the first part of its movement since at this time the tripping spindle 1109 is rotated, the selected pair of brushes 1112 and 1113 are tripped and during the subsequent upward movement of the switch shaft the brushes of these brush sets are caused to wipe over the terminals of the "banks to which they have access until the test brush 1104 engages a terminal in the test bank 1105 corresponding to the group setting of the code registers. This terminal has ground potential connected thereto, through the wipers of the code register. A circuit is now established, extending from grounded battery through the right hand winding of control relay 644, the left hand contacts of sequence switch cam 605, conductor 1106, test brush 1104, bank terminal 1114, conductor 1115, contact 830 and wiper 831 of the code register B, conductor 832, contact 833 and wiper 834 of the code register A, conductor 835 and thence to ground at the lower left hand contact of sequence switch cam 608 (1 to 5). Upon the closure of this circuit through the right hand-wind ing of relay 644, the relay is differentially balanced and deenergizes, =opening at its armature and front contact the circuit extending through up drive magnet 1110 of the switch TS to arrest the upward move ment of the switch shaft and to position the selected sets of brushes beneath the groups of bank terminals corresponding to the setting of the code registers A and B, and closing at its armature and back contact a circuit extending through the upper left hand contact of sequence switch cam 607 (4) for driving sequence switch 600 out a of sequence switch 602 but is again established as soon as the sequence switch reaches position 5. Relay 644, upon, reenergizing, V

closes a circuit for driving sequence switch 600 out of position 5 and into position 6, which circuit extends from battery through the winding of sequence switch :magnet 600,

the left hand contact of sequence switch cam 603 (5) and to ground at the armature and front contact of relay 644.

In position 6 sequence switch 600 again closes the circuit extending over sequence switch earn 604 and conductor 1101 and 3 through the up drive magnet 1100 of trans lator switch TS. The up drivemagnet is thereupon energized causing the movement of the selected sets of brushes of the trans lator switch over the selected group of ter minals in the bank to which the selected sets of brushes have access, and until test brush 1104 engages a contact in thebank 1105 upon which ground potential has been placed b a circuit extending through-the wiper o' the code register C. Upon the engagementof the test brush 1104 with this 8 terminal 1116, a circuit is established through the right hand winding of relay 644,.which may be traced from grounded battery through the right hand winding of relay 644, the left hand contacts of sequence switch cam 605, conductor 1106, test brush 1104, terminal 1116, conductor 1117, contact 836 and wiper 837 of the code register C,

ture andback contact closes a circuit extending through the magnet of sequence switch 600, and through the upper left hand contact of sequence switch cam 607 (6) for driving the sequence switch 600 out of position 6 and into position 8. In passing out of position 6 the initial energizing circuit of relay 644 is opened at the contact of sequence switch cam 602, and in passing into position 7 a circuit is established for relays 1118 and 1119, which circuit may be traced from grounded battery through the'windings of these relays in parallel, conductor 1120, the right hand armature and back contact of relay 1121; conductor 1122 and thence to ground through the upper right hand contact of sequence switch cam 606 (7 to 14). Relays 1118 and 1119, upon energizing, connect the brushes of the brush sets 1112 and 1113 to the windings of translator register control relays 1000, 1001, 1002, 1003, 1004' and 1005.

Durin the setting of the translator switch S and immediately following the setting ofthe code registers A, B and C, the calling subscriber has proceeded to dial the four numerical digits of the number of the desired line causing the setting of the wipers of the thousands register TH upon the ninth set of contacts in the respective banks to which these wipers have access, the settin of the wipers of the hundreds register li upon the fifth set of contacts in the respective banks to which these wipers have access, the setting of the wipers of the tens register T upon the third set of contacts in the banks to which these wipers have access and the setting of the wipers of the units register U upon the second set of contacts in the banks to which these wipers have access. Following the setting of the units register U, the register steering switch RS moves its wipers to position 7 in which position a circuit is established for advancing the time measure switch TM from position 6 into position 16, this circuit extending from grounded battery through the stepping magnet 626 of the time measure switch, wiper 627, the tied contacts of the bank with which this wiper is associated, interrupter 645, conductor 839, No. 7 contact 840 in the bank with which wiper 804 of steering switch BS is associated, wiper 804, conductor 803 and thence to ground through the make contacts of the right hand armature of relay 802.

Setting the translator register relays.

Upon the connection of the translator register relays 1000 to 1005 inclusive with the brushes of the brush sets 1112 and 1113 of the translator switch TS, impulses are transmitted thereto from the pulse machine drtun 1123. In the case assumed, two impulses are transmitted from grounded battery through the brush 1124, ring 1125, segments 1126, brush 1127, bank terminal 1128, brush 1129, conductor 1130, inner left hand armature and front contact of relay 1118, conductor 1131, thence to ground through the winding of class register control relay 1000. Similarly a circuit is es tablished from grounded battery through brush 1124, ring 1125, segment 1132, brush 1133, bank terminal 1134, brush 1135, conductor 1136, the inner right hand armature and front contact of relay 1118, conductor 1137 thence to ground through the winddistrict group register control relay 1003"- may be traced from grounded battery through brush- 1124, ring 1125, segment- 1138, brush 1139, bank terminal 1144, brush 1145, conductor 1146, the inner left hand armature and front contactof relay 1119,

conductor 1147 and thence to ground through the winding of relay 1003. The

circuit of office group register control relay 1004 may be traced from grounded battery through brush 1124, ring. 1125, segment 1132, brush 1133, bank terminal 1148, brush 1149, conductor 1150, the inner ri ht hand armature and front contact of re ay 1119, conductor 1151, and thence to ground through the winding of relay 1004. The talking selection register control relay 1005 is energized 1125, segment 1132, brush 1133, bank terminal 1152, brush 1153, conductor 1154, the outer right hand armature and front contact of relay 1119, conductor 1155, and thence to ground through the winding of relay 1005.

Control relay 1000 upon energizing, closes a circuit for energizing relays 1006 and 1007 extending from grounded battery through 'the windings of these relays in parallel and thence to ground through the armature and front contact of relay 1000,'and the impulses received from the drum ofthe pulse machine by relay 1000 will thus be transmitted to the windings of relays 1006 and 1007. As soon as the pulse machine has rotated the drum to a point-where the brush 1127 engages the first segment 1126 and relays 1000, 1006 and 1007 are thus energized, a circuit will be closed for the class register relay 1008 which circuit may be traced from grounded battery, through brush 1124, ring 1125, segment 1156, brush 1157, conductor 1158, the inner left hand armature and front contact of relay 1006, and thence through the right, hand winding of class register relay. 1008 to ground. This relay, upon energizing, closes a locking circuit for itself extending from grounded battery through the upper left hand contact of sequence switch-cam 610 (7 to 14 conductor 646, conductor 1010 and thence through the.

over a circuit extending from grounded battery through brush 1124, ring 

